An estimated 36 million people worldwide have HIV infection, while over 300 million have HBV infection. Among those with HBV mono-infection, HBe seroconversion from the state of Hepatitis B e antigen (HBeAg) positive chronic hepatitis to an "inactive" or "carrier" state (HBeAg negative) has historically been considered to mark a change in HBV infection phase or stage and results in a better prognosis. Patients who experience spontaneous HBeAg seroconversion can have reduction in hepatic fibrosis and "inactive carrier status" patients have more favorable outcomes, with lower incidence of cirrhosis and hepatocellular carcinoma (HCC). The association of HBeAg seroconversion with better outcome may be due to its association with reduction in HBV viral load as HBV DNA level has been shown to be independently associated with risk of HCC. When compared with HBV mono-infection, HIV-HBV co-infection increases risk of liver-related mortality. However there is little information on the virologic and serologic outcomes of those with HIV-HBV coinfection. National HIV guidelines recommend the initiation of HIV antiretroviral therapy (ART) that includes 2 active HBV agents in order to prevent development of drug resistance to HBV. Yet some experts argue that there is insufficient data to warrant dual HBV therapy immediately and that it is reasonable to sequence a second HBV agent if monotherapy does not suppress HBV after 48-96 weeks. Furthermore, limited data suggest that persons with HIV-HBV coinfection are less likely to achieve HBV viral suppression and less likely to lose HBeAg and develop anti-HBe. The AIDS Clinical Trials Group (ACTG) Longitudinal Linked Randomized Trials (ALLRT) study is a well characterized cohort of 4371 HIV-infected subjects who have been prospectively randomized to receive ART and have stored samples at a central repository. We therefore propose to identify those subjects with active HBV infection among this ideal cohort and as our primary objective compare the time to HBV virologic suppression and change in HBeAg/anti- HBe status among those who receive 2 HBV active agents compared with those who receive one HBV active agent over a 5 year period. We will also evaluate for Hepatitis D co-infection, genotype for markers of prognosis and perform resistance testing on those who never suppress or have rebound HBV viremia on therapy. Further characterizing the disease course of HIV-HBV coinfection will assist in development of future pathogenesis studies and treatment interventional trials. PUBLIC HEALTH RELEVANCE: Hepatitis B Virus (HBV) infection is a significant cause of morbidity and mortality among those with Human Immunodeficiency Viral (HIV) infection. There is limited data on the effectiveness of combination therapies used to treat both HIV and HBV compared with HIV therapies that contain only one active drug against HBV. This proposal will examine the effectiveness of HBV treatment by measuring hepatitis markers and the amount of Hepatitis B virus in stored blood samples from HIV-HBV coinfected patients who participated in prospective, longitudinal randomized HIV clinical trials.